From fb8e37f35a2fe1f983ac21850e856e2c7498d469 Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Wed, 30 Jun 2021 18:49:09 -0700
Subject: [PATCH] mm/pagemap: export uffd-wp protection information

Export the PTE/PMD status of uffd-wp to pagemap too.

Link: https://lkml.kernel.org/r/20210428225030.9708-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Oliver Upton <oupton@google.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Wang Qing <wangqing@vivo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 Documentation/admin-guide/mm/pagemap.rst | 2 ++
 fs/proc/task_mmu.c                       | 9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
index 340a5aee9b80..fb578fbbb76c 100644
--- a/Documentation/admin-guide/mm/pagemap.rst
+++ b/Documentation/admin-guide/mm/pagemap.rst
@@ -21,6 +21,8 @@ There are four components to pagemap:
     * Bit  55    pte is soft-dirty (see
       :ref:`Documentation/admin-guide/mm/soft-dirty.rst <soft_dirty>`)
     * Bit  56    page exclusively mapped (since 4.2)
+    * Bit  57    pte is uffd-wp write-protected (since 5.13) (see
+      :ref:`Documentation/admin-guide/mm/userfaultfd.rst <userfaultfd>`)
     * Bits 57-60 zero
     * Bit  61    page is file-page or shared-anon (since 3.5)
     * Bit  62    page swapped
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 9feda7792882..95c8f1e8fea6 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1302,6 +1302,7 @@ struct pagemapread {
 #define PM_PFRAME_MASK		GENMASK_ULL(PM_PFRAME_BITS - 1, 0)
 #define PM_SOFT_DIRTY		BIT_ULL(55)
 #define PM_MMAP_EXCLUSIVE	BIT_ULL(56)
+#define PM_UFFD_WP		BIT_ULL(57)
 #define PM_FILE			BIT_ULL(61)
 #define PM_SWAP			BIT_ULL(62)
 #define PM_PRESENT		BIT_ULL(63)
@@ -1375,10 +1376,14 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm,
 		page = vm_normal_page(vma, addr, pte);
 		if (pte_soft_dirty(pte))
 			flags |= PM_SOFT_DIRTY;
+		if (pte_uffd_wp(pte))
+			flags |= PM_UFFD_WP;
 	} else if (is_swap_pte(pte)) {
 		swp_entry_t entry;
 		if (pte_swp_soft_dirty(pte))
 			flags |= PM_SOFT_DIRTY;
+		if (pte_swp_uffd_wp(pte))
+			flags |= PM_UFFD_WP;
 		entry = pte_to_swp_entry(pte);
 		if (pm->show_pfn)
 			frame = swp_type(entry) |
@@ -1426,6 +1431,8 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
 			flags |= PM_PRESENT;
 			if (pmd_soft_dirty(pmd))
 				flags |= PM_SOFT_DIRTY;
+			if (pmd_uffd_wp(pmd))
+				flags |= PM_UFFD_WP;
 			if (pm->show_pfn)
 				frame = pmd_pfn(pmd) +
 					((addr & ~PMD_MASK) >> PAGE_SHIFT);
@@ -1444,6 +1451,8 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
 			flags |= PM_SWAP;
 			if (pmd_swp_soft_dirty(pmd))
 				flags |= PM_SOFT_DIRTY;
+			if (pmd_swp_uffd_wp(pmd))
+				flags |= PM_UFFD_WP;
 			VM_BUG_ON(!is_pmd_migration_entry(pmd));
 			page = migration_entry_to_page(entry);
 		}